Is it leaking on the side of the portafilter or what you mean is the dose is short? if dose is short, you can calibrate by pressing the fifth button on that group about 5 sec. then it will blink. prepare you grind in the portafilter then put it in the group. brew with the appropriate button the manually stop at the right level or quantity in the cup. you can do this with all the doses you require. Now by pressing the fifth button again 5 sec. you can exit programming mode.